INTRODUCTION: Noise is increasingly recognised as a potentially important environmental pollutant but most studies on human responses to noise exposure relate to steady state situations. Effects may differ when noise changes rapidly, e.g. after noise mitigation interventions or with changes in road or airport configurations.

METHODS: A systematic review of studies on human reactions to changes in environmental noise exposures published from 1980 to March 2011 was conducted.

RESULTS: 41 papers satisfied the inclusion criteria. The most commonly studied outcomes were annoyance (23 papers) and sleep disturbance (11 papers). Other reactions were well-being, activity disturbance and use of living environment. No studies including physiological or disease measures were identified. The most commonly used study design was a written survey. Studies were methodologically diverse and it was not possible to conduct a formal meta-analysis. Annoyance was not necessarily decreased by reducing noise exposure. Non-acoustical factors influenced annoyance ratings and some of these were not identical to those in steady state conditions. There was insufficient evidence to recommend sleep disturbance as an alternative measure of reactions in changed noise conditions.

CONCLUSIONS: Surveys of health effects in changed noise situations should be conducted both before and after the change. Annoyance as a reaction indicator should be evaluated with caution as non-acoustical factors play an important role in annoyance ratings. Technical interventions reducing noise levels may therefore not have impacts on annoyance proportionate to their impacts on sound levels. Further studies, investigating impacts on health endpoints (e.g. blood pressure) in changed noise situations are needed.